Dental machine control



April 1, 1952 J. A. BIGGS DENTAL MACHINE CONTROL Filed July 6, 1950Patented Apr. 1, 1952 UNITED STATES PATENT OFFICE.

DENTAL MIACIIINE CONTRQL Justin Allen Biggs, J acksonville. 111.

Application July 6, 1950 Serial No. 17 2,,330

My invention relates to mercury switches for dental machines and has todo with a means of automatically turning on and shutting off theelectric current.

An object of this invention is to make it convenient; practical andserviceable for a dentist to operate a dental drill throughout the hoursof his daily dental service without having to keep his feet constantlypressing on a foot switch in a certain position to keep the drill going.

In the construction of a dental machine there are hingedly connectingextension arms that are normally moved hingedly to an upright positionwhen the drill is shut off but are tilted down to an extended positionwhen the operating drill is turned on and in use.

It is therefore my particular purpose of this invention to provide avery effective comfort for a dentist wherein he will be able to work ashe stands in any desired working position around his dental chairwithout the tiring and nerve testing experience of trying to keep onefoot in a certain position all daylong on a foot switch.

I achieve the purposes of my invention by the device described in thespecification, defined in the claim and shown in the drawings wherein:

Fig. 1 is a perspective of my mercury switch secured to a drill supportarm.

Fig. 2 is a detail in an exploded view showing the relative operatingposition of the several parts of my mercury switch.

Fig. 3 is a side view of my switch and its supporting arm when the drillis shut off with the extension arm upright in position on a hook. Thedotted lines show this arm in position for use where the switch willenergize the drill.

Fig. 4 shows a quarter section interior detail in perspective.

I shall now disclose the essential convenient and novel features of myinvention as I point out the ease and comfort with which it is operated.

Dentists heretofore have had to stand from hour to hour with one foot ona drill energizing switch in order to do his work on teeth; but now withmy new mercury switch the instant he lifts the drill off its supportinghook then he moves it over in an extended position toward his patientwhere the drill support arm tilts forwardly and downwardly causing themercury in my switch to energize the drill ready for drilling and readyto keep it running until the dentist is ready to shut it off, without inany manner controlling its energizing switch with his foot.

I shall now show how I accomplish this outstanding improvement with mydevice.

1 Claim. (CI. 32-26) It is first essential that I provide. a sturdymounting for support of my switch and I therefore removably secure mycylindrical drum I to the inside of its bracket housing 2 in a mannerpermitting drum I to beturned to right'or-left slightly on its axis 3when-needed.

Housing 2 is preferably clamped or bolted; to drill support arm 4; downabout the elbow 5 thereof to make a good firm operative support for'iton arm 4 at a position where no swivel action will be required as is thecase normally with the middle portion 6 of arm 4, to permit a greaterfreedom of movement of a dentist's drill 'I when in use, since themiddle portion 6 of arm 4 will freely swivel in its connection withelbow 5 of arm 4.

Housing 2 may well be held to arm 4 elbow 5 by a set screw 8 engaging aclamp strap 9 about elbow 5 of this arm 4, so that in this operativeposition the mercury switch unit may function correctly.

Since housing 2 is secured to elbow 5 of arm 4 it turns only with arm 4and that is when drill I is lifted into a position for use oiT of itssupport hook on the dental machine, not shown.

Yet the amount of movement of housingZ is but little even with arm 4.

Note that drum I has a pair of opposed pockets Ill and II containingmercury I2 and I3 respectively. A wire I4 having one end I5 secured todrum section I6 contacts mercury I2 through its securing point II; whilethe other end I8 of wire I4 contacts mercury I3 through its securingpoint I9.

While housing 2 is fixed on elbow 5 of arm 4, yet drum I is slightlymovable rotatably on its axis 20 within housing 2.

Here, it will be noted that drum I has a simple and handy means foradjusting it slightly for a setting as needed. The means for selectivelysetting the rotated position of drum I is provided in a claw 2| withfinger 22 thereof engaging a peripheral recess 23 and fingers 24 and 25gripping the side 25 of drum I; while the control axis 27 of claw 2!resting in an insulation bearing 28 of housing 2 has a thumb and fingerknob 29 by which the adjusting claw 2| is turned for a selectivesetting.

In drum I is a central plate 36 of insulation material and is providedwith a peripheral aperture 3I, and this plate is fixed in its centralposition in drum I to define an insulating partition plate 30 betweenmercury pocket I0 and opposed mercury pocket II for mercury I2 and I3respectively.

Note then that a dentist who is tall need not extend drill support arm 4as far as a shorter dentist would and that is why an adjustment needs tobe made in the selected position of rotation of drum I, since when arm 4is upright and not tilted to a position for use, then aperture 3'! willbe set to a level above the mercury in pockets I and I I where the drillwill not be energized; but when the dentist lifts drill 1 off of itssupport hook 32, then arm 4 moving to an extended position downwardlyand outwardly will cause drum I in housing 2 to turn that much with arm4, thus tipping aperture 3| forward far enough to move it down under themercury surface level where mercury I2 and I3 from opposed pockets I0and II respectively will at once merge through this aperture 3| in plate30 thus closing the drill energizing electric circuit through wire I4whose adjacent ends are connected to mercury I2 and I3 respectively inpockets I0 and II respectively.

Wire I4 is connected with a source of electric energy (not shown) andthe make and break mercury switch efiectively connects and disconnectswire I4 in its operative functioning with this source of electric energyfor running drill 1.

Thus a lot of fatiguing annoyance and discomforture is eliminated by mynew and novel construction and service of mercury switch.

I have described and now I claim as my invention:

A dental machine in combination with a mercury switch and comprising ajointed extension drill support arm, a dental drill rotatably operativeat the free end thereof, a motor for actuating said drill and a cableestablishing drill control connection between said motor and said drill,a mercury switch operatively supported at the elbow joint of said drillsupport arm in position where said arm cannot be extended from a foldedposition for operation without automatically energizing the drill.

JUSTIN ALLEN BIGGS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Dec. 28, 1934

